Hyperactivity linked to inner-ear defect

Saturday

Sep 14, 2013 at 12:01 AMSep 15, 2013 at 1:01 PM

When hyperactivity is found in children with severe hearing loss, it often is assumed to stem from frustrations they have communicating or socializing. But a new study says a genetic defect in the inner ear also might play a role.

When hyperactivity is found in children with severe hearing loss, it often is assumed to stem from frustrations they have communicating or socializing. But a new study says a genetic defect in the inner ear also might play a role.

Researchers at the Albert Einstein College of Medicine in the Bronx caused a loss of hearing and sense of balance in young mice by knocking out a gene called Slc12a2.

The removal of the gene also resulted in higher levels of two proteins in a part of the brain that helps regulate motor functions. The mice then displayed hyperactive behavior.

When the researchers lowered levels of the proteins, the behavior returned to normal.

Precisely which neural pathway from the ear to the brain was active in this case is not yet clear, researchers said.

They also noted that the study, published in the journal Science, potentially identified only a single source of hyperactivity, which is likely to have many causes.

Male development gene affects men differently

The gene responsible for activating male development is surprisingly unstable, leaving the pathway to male sexuality fraught with inconsistency, a study finds.

The SRY gene on the Y chromosome sets off the growth of male sex organs in human embryos. To study the gene, researchers at Case Western Reserve University looked at families in which daughters inherited a Y chromosome, a rare occurrence in which SRY fails to fire, leaving a genetically male embryo to develop as a sterile female.

They found that SRY is highly vulnerable to environmental factors, leading to a wide divergence of testosterone-related male attributes, such as muscle mass, from one man to another, the study, which was published in the Proceedings of the National Academy of Sciences, says.